Survey on Photo-Voltaic Powered Interleaved Converter System

Renewable energy is the best solution to meet the growing demand for energy in the country. The solar energy is considered as the most promising energy by the researchers due to its abundant availability, eco-friendly nature, long lasting nature, wide range of application and above all it is a maintenance free system. The energy absorbed by the earth can satisfy 15000 times of today’s total energy demand and its hundred times more than that our conventional energy like coal and other fossil fuels. Though, there are overwhelming advantages in solar energy, It has few drawbacks as well such as its low conversion ratio, inconsistent supply of energy due to variation in the sun light, less efficiency due to ripples in the converter, time dependent and, above all, high capitation cost. These aforementioned flaws have been addressed by the researchers in order to extract maximum energy and attain hundred percentage benefits of this heavenly resource. So, this chapter presents a comprehensive investigation based on photo voltaic (PV) system requirements with the following constraints such as system efficiency, system gain, dynamic response, switching losses are investigated. The overview exhibits and identifies the requirements of a best PV power generation system

Contributions to Modulation and Control Algorithms for Multilevel Converters

Las actuales tendencias de la red eléctrica han lanzado a la industria a la búsqueda de sistemas de generación, distribución y consumo de energía eléctrica más eficientes. Generación distribuida, reducción de componentes pasivos, líneas DC de alta tensión son, entre otras, las posibles líneas de investigación que están actualmente siendo consideradas como el futuro de la red eléctrica. Sin embargo, nada de esto sería posible si no fuera por los avances alcanzados en el campo de la electrónica de potencia. El trabajo aquí presentado comienza con una breve introducción a la electrónica de potencia, concretamente a los convertidores de potencia conectados a red, sus estrategias de control más comunes y enfoques ante redes desbalanceadas. A continuación, las contribuciones del autor sobre el control y modulación de una topología particular de convertidores, conocidos como convertidores multinivel, se presentan como el principal contenido de este trabajo. Este tipo de convertidores mejoran la eficiencia y ciertas prestaciones, en comparación con convertidores más tradicionales, a costa de una mayor complejidad en el control al incrementar la cantidad de los componentes hardware. A pesar de que existen numerosas topologías de convertidores multinivel y algunas de ellas son brevemente expuestas en este trabajo, la mayoría de las aportaciones están enfocadas para convertidores del tipo diode-clamped converter. Adicionalmente, se incluye una aportación para convertidores del tipo multinivel modular, y otra para convertidores en cascada. Se espera que el contenido de la introducción de este trabajo, junto a las contribuciones particulares para convertidores multinivel sirva de inspiración para futuros investigadores del campo

Challenges of Inductive Electric Vehicle Charging Systems in both Stationary and Dynamic Modes

Inductive power transfer as an emerging technology has become applicable in wide power ranges including Electric Vehicle, Electric Aircraft, wheelchair, cellphone, scooter and so on. Among them, inductive Electric Vehicle (EV) charging has gained great interest in the last decade due to many merits namely contactless technology, more convenience, full automotive charging process. However, inductive EV charging systems could bring about so many issues and concerns which are addressed in this dissertation. One of the critical challenges addressed in this dissertation is a virtual inertia based IPT controller to prevent the undesirable dynamics imposed by the EVs increasing number in the grid. Another adverse issue solved in this dissertation is detecting any metal object intrusions into the charging zone to the Inductive Power Transfer (IPT) systems before leading to heat generation on the metal or risk of fire. Moreover, in this dissertation, a new self-controlled multi-power level IPT controller is developed that enables EV charging level regulation in a wide range of power; suitable for different applications from golf-cart charging system (light duty EV) to truck (heavy duty EV). The proposed controller has many merits including easy to be implemented, cons-effective, and the least complexities compared to conventional PWM methods. Additionally, in this dissertation, the online estimation of IPT parameters using primary measurement including coupling factor, battery current and battery voltage is introduced; the developed method can find immediate applications for the development of adaptive controllers for static and dynamic inductive charging systems. Finally, the last objective of this research is physics-based design optimization techniques for the magnetic structures of inductive EV charging systems for dynamic application (getting charged while in motion). New configuration of IPT transmitting couplers with objective of high-power density, low power loss, low cost and less electromagnetic emission are designed and developed in the lab

Novel design techniques and control schemes for higher efficiency switched-mode power converters

This thesis details novel control schemes and design techniques with the aim of improving the performance of several switched-mode power converter topologies. These improvements include higher steady-state and transient efficiencies for hard-switching converters and the automatic current limiting provision for LLC resonant converters. The thesis initially attempts to use linear closed-loop controllers to improve the transient response of synchronous buck converters, enabling them to be designed with a lower open-loop bandwidth so that the system can achieve higher efficiency. Three types of controllers were investigated viz: the PID, the state-feedback and the predictive controller. All three controllers exhibit similar step responses, which are the maximum transient responses achievable by the linear controllers with the given requirements. The thesis then examines the parallel converter (i.e. a converter with two parallel connected power modules (PMs)) in detail with a view to improve the efficiency and to minimise the current ripple experienced by the output capacitor. Two control schemes and a design technique for the parallel converter are proposed, to simultaneously improve its efficiency and power density. The parallel converter in this research consists of two non-identical rated PMs (termed main PM and auxiliary PM), with the transient response requirement allocated to the auxiliary PM, thereby allowing the main PM to operate at a lower frequency for higher steady-state efficiency. The first control scheme activates the auxiliary PM only when a pre-determined deviation in load/output voltage is exceeded under a load step. Thus, eliminating the losses contributed by the low efficiency auxiliary PM for small load step changes. The second control scheme shapes the auxiliary PM inductor current to be equal and opposite to the main PM current ripple, which when combined reduce the current ripple as experienced by the output filter capacitor, thereby allowing a lower value (and hence physically smaller) capacitor to be selected for higher power density. In order to improve the converter's steady-state efficiency further, the minimum load condition is allocated to the auxiliary PM in the new design technique. These allow both the main PM inductance and its switching frequency to be lower for higher efficiency. In recent years, the LLC has received much attention owing to its favourable operating characteristics including high efficiency and high power density. Usually one chooses to operate at or very close to the load independent point (LIP) since very little control effort is required to regulate the converter's output voltage in response to changes in the load. However under fault conditions where the load tends towards a short circuit, excessive currents can flow and thus control action need to be taken to protect both the converter and the load. The final topic of the thesis hence studies the characteristics of an LLC resonant converter with current-limiting capacitor-diode clamp and develops a new equivalent circuit model to predict the behaviour under overload conditions. A detailed analysis of the converter is presented using the proposed model, from which a design methodology is derived allowing the optimum circuit components to be selected to achieve the required current limiting/protection characteristics

High Frequency Power Converter with ZVT for Variable DC-link in Electric Vehicles

abstract: The most important metrics considered for electric vehicles are power density, efficiency, and reliability of the powertrain modules. The powertrain comprises of an Electric Machine (EM), power electronic converters, an Energy Management System (EMS), and an Energy Storage System (ESS). The power electronic converters are used to couple the motor with the battery stack. Including a DC/DC converter in the powertrain module is favored as it adds an additional degree of freedom to achieve flexibility in optimizing the battery module and inverter independently. However, it is essential that the converter is rated for high peak power and can maintain high efficiency while operating over a wide range of load conditions to not compromise on system efficiency. Additionally, the converter must strictly adhere to all automotive standards. Currently, several hard-switching topologies have been employed such as conventional boost DC/DC, interleaved step-up DC/DC, and full-bridge DC/DC converter. These converters face respective limitations in achieving high step-up conversion ratio, size and weight issues, or high component count. In this work, a bi-directional synchronous boost DC/DC converter with easy interleaving capability is proposed with a novel ZVT mechanism. This converter steps up the EV battery voltage of 200V-300V to a wide range of variable output voltages ranging from 310V-800V. High power density and efficiency are achieved through high switching frequency of 250kHz for each phase with effective frequency doubling through interleaving. Also, use of wide bandgap high voltage SiC switches allows high efficiency operation even at high temperatures. Comprehensive analysis, design details and extensive simulation results are presented. Incorporating ZVT branch with adaptive time delay results in converter efficiency close to 98%. Experimental results from a 2.5kW hardware prototype validate the performance of the proposed approach. A peak efficiency of 98.17% has been observed in hardware in the boost or motoring mode.Dissertation/ThesisMasters Thesis Electrical Engineering 201

Industrial and Technological Applications of Power Electronics Systems

The Special Issue "Industrial and Technological Applications of Power Electronics Systems" focuses on: - new strategies of control for electric machines, including sensorless control and fault diagnosis; - existing and emerging industrial applications of GaN and SiC-based converters; - modern methods for electromagnetic compatibility. The book covers topics such as control systems, fault diagnosis, converters, inverters, and electromagnetic interference in power electronics systems. The Special Issue includes 19 scientific papers by industry experts and worldwide professors in the area of electrical engineering

Power Management ICs for Internet of Things, Energy Harvesting and Biomedical Devices

This dissertation focuses on the power management unit (PMU) and integrated circuits (ICs) for the internet of things (IoT), energy harvesting and biomedical devices. Three monolithic power harvesting methods are studied for different challenges of smart nodes of IoT networks. Firstly, we propose that an impedance tuning approach is implemented with a capacitor value modulation to eliminate the quiescent power consumption. Secondly, we develop a hill-climbing MPPT mechanism that reuses and processes the information of the hysteresis controller in the time-domain and is free of power hungry analog circuits. Furthermore, the typical power-performance tradeoff of the hysteresis controller is solved by a self-triggered one-shot mechanism. Thus, the output regulation achieves high-performance and yet low-power operations as low as 12 µW. Thirdly, we introduce a reconfigurable charge pump to provide the hybrid conversion ratios (CRs) as 1⅓× up to 8× for minimizing the charge redistribution loss. The reconfigurable feature also dynamically tunes to maximum power point tracking (MPPT) with the frequency modulation, resulting in a two-dimensional MPPT. Therefore, the voltage conversion efficiency (VCE) and the power conversion efficiency (PCE) are enhanced and flattened across a wide harvesting range as 0.45 to 3 V. In a conclusion, we successfully develop an energy harvesting method for the IoT smart nodes with lower cost, smaller size, higher conversion efficiency, and better applicability. For the biomedical devices, this dissertation presents a novel cost-effective automatic resonance tracking method with maximum power transfer (MPT) for piezoelectric transducers (PT). The proposed tracking method is based on a band-pass filter (BPF) oscillator, exploiting the PT’s intrinsic resonance point through a sensing bridge. It guarantees automatic resonance tracking and maximum electrical power converted into mechanical motion regardless of process variations and environmental interferences. Thus, the proposed BPF oscillator-based scheme was designed for an ultrasonic vessel sealing and dissecting (UVSD) system. The sealing and dissecting functions were verified experimentally in chicken tissue and glycerin. Furthermore, a combined sensing scheme circuit allows multiple surgical tissue debulking, vessel sealer and dissector (VSD) technologies to operate from the same sensing scheme board. Its advantage is that a single driver controller could be used for both systems simplifying the complexity and design cost. In a conclusion, we successfully develop an ultrasonic scalpel to replace the other electrosurgical counterparts and the conventional scalpels with lower cost and better functionality